Strain and Conduction-Band Offset in Narrow n-type FinFETs

In this paper, we compare measurements of the conduction-band (CB) offset in [110]- and [010]-oriented narrow n-type FinFETs with a model taking into account both strain and quantum confinement. We estimate the complete strain tensor for the scarce strain measurement points available with finite-element-method simulations of the thermal expansion effect. We found an inhomogeneous compressive strain that increases for smaller fin widths. The experimental CB offset is extracted from temperature-dependent transfer characteristics. The results show a lowering of the CB edge up to 40 meV for fin widths down to 5 nm. These experimental observations compare well with the model, and hence, the band offset can be explained by both quantum confinement and strain.